What device is used to avoid static electric shock and ground the cargo hook?

The device used to avoid static electric shock and ground the cargo hook is a static discharge wand. This tool is specifically designed to safely dissipate any static electricity that may build up on the load or equipment during operations. By properly grounding the cargo hook, the static discharge wand helps to ensure that the operator and the equipment are protected from potential electric shocks, which can be dangerous during sling load operations.

Using a static discharge wand before connecting or disconnecting loads mitigates the risk of static discharges that can occur, particularly with materials that are prone to generating static electricity. The other options, while related to safety and grounding, do not serve the specific function of discharging static electricity or grounding the hook effectively in the context of sling load operations.